Air filter question
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Cruiser
Joined: Jan 2015
Posts: 145
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From: South Florida
Air filter question
Have a stock 09 Street Glide with Screaming Eagle slip-on's and want to know if it is worth going to a high flow filter.
Just getting ready to change it out.
Thx!
Just getting ready to change it out.
Thx!
MODERATOR
Joined: Oct 2007
Posts: 4,108
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From: New England
FWIW, just about every stock air filter will flow more then your stock motor can draw. In most every case, a "high flow" filter will get you nothing but a hole in your bank account.
Yes, I know people really hate to hear that but it's the truth.
As to a tune...only a full-featured tune is worth doing. Unless you're going to set the VE's correctly to begin with, adjusting only the AFR is a complete waste of time.
Yea, I know, people don't like to hear that either...
Outstanding HDF Member
Joined: Jan 2008
Posts: 3,328
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From: Pacific Northwest
The dealer flash is garbage.
If you do the air filter you will definitely need to re-tune. Find a good independent shop with a dyno cell and have it done.
You will like the results - you'll pick up an easy 10hp/10lbs ft. and still get great mileage.
Having an A/C that will flow more than the motor needs is a big plus. I know of no stock A/C that'll flow more air than your motor needs. Quite the opposite is true - due to EPA noise restrictions stock A/C's are all choked up right from the factory.
Freeing up air flow only makes sense and the motor will only flow what it needs.
If you do the air filter you will definitely need to re-tune. Find a good independent shop with a dyno cell and have it done.
You will like the results - you'll pick up an easy 10hp/10lbs ft. and still get great mileage.
Having an A/C that will flow more than the motor needs is a big plus. I know of no stock A/C that'll flow more air than your motor needs. Quite the opposite is true - due to EPA noise restrictions stock A/C's are all choked up right from the factory.
Freeing up air flow only makes sense and the motor will only flow what it needs.
Last edited by Leftcoaster; Jan 13, 2015 at 12:44 PM.
Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
Likes: 402
From: Phoenix '53, '88, '09 Big Twins
The stock air cleaner is restrictive for noise emissions, it also uses a filter media which becomes clogged and flows less.
Once the air has moved through the filter it has to make a 90ş turn into the throttle body.
The stock air cleaner flows about 160 CFM
Most aftermarket hi flow air cleaners incorporate an air horn into the backing plate, this will order the air and ease that 90ş turn.
Most have a better filter media
All are less restrictive- and noisier- some riders are confused by that.
Most aftermarket hi flow air cleaners flow 250 CFM or more ( which exceeds the motors demand)
with tuning compensation* adding a hi flow air cleaner to your pipes will get you 7 to 10 reliable horsepower out of your motor..getting you to the mid-70's.
I prefer the Ness Big Sucker which can be about $125 on ebay from easternpc.
that's the chrome backing plate version which looks best with the black/chrome motor.
This comes with an oiled, reusable, washable filter which will last a lifetime.
and this AC is an easier install that most.
*tuning compensation can be done with a variety of devices depending on the owners interest in exploring complexities and budget.
I use the plug in XIEDS modules from nightrider.com- cost about $125.
others use other devices which may cost more, may offer more, but may have drawbacks.
Mike
Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
Likes: 402
From: Phoenix '53, '88, '09 Big Twins
The stock air cleaner is restrictive for noise emissions, it also uses a filter media which becomes clogged and flows less.
Once the air has moved through the filter it has to make a 90ş turn into the throttle body.
The stock air cleaner flows about 160 CFM
Most aftermarket hi flow air cleaners incorporate an air horn, this will order the air and ease that 90ş turn.
Most have a better filter media
All are less restrictive- and noisier- some riders are confused by that.
Most aftermarket hi flow air cleaners flow 250 CFM or more ( which exceeds the motors demand)
with tuning compensation* adding a hi flow air cleaner to your pipes will get you 7 to 10 reliable horsepower out of your motor..getting you to the mid-70's.
I prefer the Ness Big Sucker which can be about $125 on ebay from easternpc.
that's the chrome backing plate version which looks best with the black/chrome motor.
This comes with an oiled, reusable, washable filter which will last a lifetime.
and this AC is an easier install than others, the throttle body brace stays in place and the gas tank doesn;t need to be pulled, just loosened
*tuning compensation can be done with a variety of devices depending on the owners interest in exploring complexities and budget.
I use the plug in XIEDS modules from nightrider.com- cost about $125.
others use other devices which may cost more, may offer more, but may have drawbacks.
Mike
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Joined: Oct 2007
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From: New England
A stock 103 TC at about 4000 rpm will flow approximately 135 cfm's. At about 5000 rpm, the cfm's "jump" up to about 143.
Here's MK's previous post...Of what value does an air cleaner that flows 250, 500, or even 1000 cfm's provide?
Here's a little hint that MIGHT help you understand air flow...there's a LOT of things that reduce air volume into the cylinders that's well after the air cleaner. I'm not saying the air cleaner plays no part but it's not what causes any significant increase in air volume if nothing else downstream is done to improve air flow.
For example, smaller port creates more velocity, which in turn creates more inertia. The principle of inertia is to pack as much into any given area before it stops. The more inertia, the more force it develops, and the more mass it will pack before it stops.
So, when you figure in inertia (velocity squared x volume or cfm), it becomes apparent that velocity is more important to cylinder fill than volume. And unless you've made significant mods to the intake, heads, pistons, and so on, you won't get any significant benefit from just going to a "high flow" air cleaner.
The marketing for all these "high flow" systems generally fail to mention that in order to take advantage of their bigger numbers, the motor has to be modified to the point is can begin to draw much larger volumes of air. It is far cheaper to manufacturer, market, and sell $125 systems then it is to sell $2000 mods to take advantage of that new air cleaner.